1. Field of the Invention
The present invention relates to associative or content-addressable memory systems, and particularly to such systems for sorting data according to a plurality of relationships.
2. Description of the Related Art
Associative or content-addressable memories provide the ability to address items in the memory by the data stored in particular locations, rather than, or in addition to, by the addresses of the locations. This technology has developed based primarily on circuitry within the memory array that detects a match between a field of data stored in each location and an argument supplied as an input. In order to perform operations based on relations other than equality, such as greater than, less than, greater than or equal to, and less than or equal to, a time consuming sequence of masking and testing operations must be computed. See, for instance, Baer, COMPUTER SYSTEMS ARCHITECTURE, Section 5.5, "Associative Memory", Computer Science Press, 1980, pp 262-266; and Parhami, "Associative Memories and Processors: an Overview and Selected Bibliography", PROCEEDINGS OF THE IEEE, Vol. 61, No. 6, June 1973, pp. 722-730.
A need for high speed sorting arises in modern graphics algorithms which involve manipulating very large amounts of data for high resolution video screens, and a large number of images which overlay one another on the screen. Thus, a need to quickly sort video data to be displayed on the screen in a real time graphics application creates a need for a mechanism to sort large amounts of data quickly.
Further, the need arises to sort a given set of data according to a variety of relationships.
Accordingly, it is desirable to provide a memory system which allows for very fast sorting of data according to one or more selectable relationships.